Quick note: This guide is for education. Stock plan tax reporting can be tricky and rules can change. If you have multiple jobs, large vests, or complex brokerage reporting, a quick review can save money and stress.
Contents
- RSUs in one minute
- The RSU timeline: grant, vest, sell
- How RSUs are taxed on your paycheck
- Are you taxed twice?
- Forms you will see: W-2, 1099-B, 8949
- The big mistake: cost basis and overpaying
- Common scenarios: sell-to-cover, same-day sale, holding
- Capital gains basics and California notes
- Wash sales in plain English
- Planning tips: withholding and estimated taxes
- What to gather at tax time
- FAQ
RSUs in one minute
- At vesting: RSUs are treated like wages. The value on vest day is taxable income and typically shows up on your W-2.
- At selling: you are taxed only on the change in value after vesting (capital gain or loss).
- The most common problem: incorrect cost basis on your 1099-B can make it look like you had extra gains, which can lead to overpaying.
The RSU timeline: grant, vest, sell
RSUs usually have three stages. Only vesting and selling are tax events for most employees.
| Stage | What happens | Typical tax treatment |
|---|---|---|
| Grant | Your company promises shares if you meet vesting conditions. | Usually no tax at grant for RSUs. |
| Vesting | Shares become yours on a vest date. | Wages. The fair market value at vest is taxable income and appears on your W-2. |
| Sale | You sell some or all shares through your broker. | Capital gain or loss based on sale price minus your cost basis (usually the vest value). |
Simple example
100 RSUs vest when the stock is $50. You have $5,000 of wage income. If you later sell at $52, you have a $2 per share capital gain, or $200 total, not another $5,000.
How RSUs are taxed on your paycheck
Most employers treat RSU vesting like supplemental wages (similar to a bonus). That means the withholding you see on a vest paycheck may be different from your normal paycheck.
Key point
Withholding is a prepayment. Your final tax is based on your total income and credits for the year, not the flat withholding rate used on vest day.
Federal withholding (common approach)
Employers often withhold federal income tax on supplemental wages using a flat rate method (commonly 22% for many situations, with a higher mandatory rate once supplemental wages exceed $1 million in a year). See IRS Pub. 15 for the current rules.
IRS Publication 15 (PDF)California withholding (common approach)
California also has separate supplemental wage withholding rules. Many stock plan payments fall under flat-rate withholding in California. See EDD DE 231PS for details.
EDD DE 231PS (PDF)Why people still owe after big vests
If your total income puts you in a higher bracket, a flat withholding method can be lower than your effective tax rate. That can create a balance due at filing time unless you adjust withholding or make estimated payments.
Are you taxed twice?
Usually, no. It can feel like it because you see taxes on your W-2 and also see a 1099-B for stock sales. But those forms are reporting two different things.
- Vesting tax: ordinary income tax on the fair market value at vest. This is treated like wages and is included on your W-2.
- Sale tax: capital gain or loss on the change in value after vesting. This is reported through your brokerage and then on your tax return.
Mini example
Vest at $50 and sell at $50.50. You already paid wage tax on $50. You report a capital gain on $0.50 per share, not another round of wage tax.
Forms you will see: W-2, 1099-B, 8949
W-2 (from your employer)
Your RSU vest income is typically included in wages and the taxes withheld show up in the federal and state withholding boxes. The W-2 is the proof that the vest value was already treated as compensation.
1099-B (from your broker)
Your broker reports stock sales on Form 1099-B. It includes proceeds and may include cost basis and wash sale information.
IRS Instructions for Form 1099-BForm 8949 and Schedule D (on your tax return)
Form 8949 is used to report the details of sales and to reconcile what the broker reported with what you report, including basis adjustments. Totals flow to Schedule D.
The big mistake: cost basis and overpaying
This is where many people accidentally overpay: the broker 1099-B may show a cost basis that is incomplete for stock plan shares. If you enter the sale as-is without adjusting, it can look like you had a much larger gain than you actually did.
What to watch for
- 1099-B shows basis $0 or a basis that does not match the vest value.
- Your tax software shows a big gain even though you sold right after vesting.
- You see vest income on your W-2 and it feels like you are paying tax again.
What your basis usually should be
For many RSU sales, your cost basis is generally the fair market value on the vest date (the amount already included as wages), plus any amount you paid for the shares (often $0 for RSUs). Your broker might not show that full basis automatically.
How to fix it (high level)
- Start with the proceeds and the basis reported on your 1099-B.
- Compare the basis to your vest statement or your stock plan release detail.
- If the basis is incomplete, report the sale on Form 8949 and make a basis adjustment so the gain reflects only the post-vest change.
Tip: IRS guidance includes common Form 8949 adjustment codes when basis is incorrect. If you are doing this in software, it may ask for an adjustment code and amount.
IRS Form 8949 adjustment codesSanity check
If you sold the shares the same day they vested, your capital gain or loss is often small. A very large gain on a same-day sale can be a sign the basis was not captured correctly.
Common scenarios: sell-to-cover, same-day sale, holding
Sell-to-cover at vesting
Many plans automatically sell some shares at vest to cover withholding taxes. You receive the remaining shares.
- The vest value is wage income and appears on your W-2.
- The shares sold to cover are still a stock sale and usually appear on your 1099-B.
- There may be a small gain or loss between vest price and sale price.
Same-day sale
If you sell right away, you are converting your stock compensation into cash and limiting market risk.
- You still report the sale on Form 8949 and Schedule D.
- If the basis is correct, the gain or loss is usually small.
Holding shares after vest
If you hold, future price movement creates capital gains or losses when you sell.
- Holding period generally determines whether gains are short-term or long-term for federal purposes.
- California does not have a lower rate for long-term capital gains.
Capital gains basics and California notes
Capital gains are taxed when you sell an asset for more than your cost basis. Capital losses occur when you sell for less than your basis. Losses can offset gains and may offset a limited amount of other income each year depending on your situation.
Federal: short-term vs long-term
In general, holding more than one year may qualify for long-term capital gain treatment at preferential rates. Holding one year or less is generally short-term and is taxed like ordinary income.
IRS Topic: capital gains and lossesCalifornia: no preferential capital gains rates
California does not have a lower rate for capital gains, so gains are taxed as ordinary income for CA purposes.
CA FTB referenceHigh income note
Some higher-income taxpayers may also owe the 3.8% Net Investment Income Tax (NIIT) on certain investment income. If you have large capital gains, it is worth planning ahead.
IRS NIIT overviewWash sales in plain English
A wash sale can happen when you sell stock at a loss and buy the same or substantially identical stock within a 30-day window around the sale. The loss may be disallowed and carried into the basis of the replacement shares.
Why this matters for RSUs
- If you sell shares at a loss but you also receive new shares from vesting within the wash sale window, you may trigger wash sale treatment.
- Wash sale reporting can show up on your 1099-B for covered securities, but you still need to review it for accuracy.
Practical tip
If you plan to harvest losses, check your vest schedule and any automatic reinvestment or purchase plans. Timing matters.
Planning tips: withholding and estimated taxes
If you have meaningful RSU income, your best strategy is to avoid surprises by adjusting early. Withholding on vest day may not line up with your household tax bracket for the year.
Simple planning checklist
- After your first big vest (or after a raise), do a quick withholding check.
- If you tend to owe, consider increasing federal withholding (W-4) and California withholding (DE 4).
- If your vests are concentrated and withholding is not enough, estimated payments may be appropriate.
If you want a walkthrough for withholding, see our guide: W-4 and California DE 4 withholding guide.
California reminder
California withholding is controlled by DE 4, separate from the federal W-4. If you update one, review the other.
What to gather at tax time
- Your W-2 (and spouse W-2 if filing jointly).
- Your brokerage 1099 package, including the detailed gain/loss statement.
- Your stock plan release statements showing vest dates, share counts, and fair market value at vest.
- Any notes about sales that were sell-to-cover or same-day sales.
- If you have multiple brokers or transferred shares, keep transfer statements and cost basis details.
Want us to review your RSUs and stock sales?
We can reconcile your vest statements with your 1099-B, confirm your cost basis reporting, and help you plan withholding so you do not get surprised at filing time.
Book a free consultationFAQ
Why did my paycheck drop on vest day?
Vesting creates wage income, so payroll withholds federal and state income tax (and other payroll taxes). Many plans also sell shares to cover withholding, which changes what you receive.
If I sell right away, do I still need to report the sale?
Yes. The sale is still a brokerage transaction and typically appears on your 1099-B. Reporting it correctly helps ensure you are taxed only on any small post-vest change in price.
My 1099-B shows cost basis as $0. What should I do?
Do not ignore it. Compare the 1099-B to your vest statements. If the basis is incomplete, you generally need to report the sale on Form 8949 and adjust basis so the gain is accurate.
Do I pay tax again when I sell shares that already appeared on my W-2?
You pay wage tax on the vest value, then capital gains tax only on any price change after vesting. If reporting is done incorrectly, it can look like you were taxed twice, which is why the cost basis check is important.
Does California treat long-term capital gains differently?
California does not have a lower rate for capital gains. Gains are taxed as ordinary income for CA purposes.